Junfeng Wang

Around our Galaxy, like an invisible crown, stretches a tenuous cloud of gas heated to millions of degrees. It is called the galactic halo. Seeing this glow directly is difficult: it emits soft X-rays that are absorbed by Earth's atmosphere.

Imagine a spotlight: if you look at it from the side, it glows dim red, but if you stare straight into it, it blinds you with white-blue light. That, according to new data, is exactly what the mysterious 'little red dots' in the early universe look like. They are giant black holes, objects with gravity so strong that even light cannot escape, turned edge-on to us.

A black hole with a mass of 35,000 Suns drifts through a galaxy's gas like a barge through fog. Its gravity rakes the material ahead of it, leaving a dense trail behind — a wake of gas. Some of that gas gets pulled into the black hole, and it grows.